Hydrangea-like NiMn layered double hydroxide grown on biomass-derived porous carbon as a high-performance supercapacitor electrode

Layered double hydroxides (LDHs) are considered prospective candidates for supercapacitor electrodes owing to their substantial theoretical capacity and high degree of customizability. However, their poor conductivity and self-stacking tendency hinder the achievement of high-performance electrochemical characteristics. Herein, a novel CSC@NiMn LDH composite is prepared from hydrangea-like NiMn LDH grown on celery stem-derived porous carbon (CSC) through a one-step hydrothermal method. This unique anchoring structure leads to fast charge transfer between NiMn LDH and CSC, solving the issue of poor conductivity and facilitating the cyclic performance. Furthermore, the hydrangea-like morphology and uniform dispersion of NiMn LDH, along with the three-dimensional porous architecture of CSC, enhance the accessibility of active sites, offer efficient and brief pathways for electrolyte penetration and ion transport, thereby facilitating the electrochemical reaction process. Consequently, the optimal CSC@NiMn LDH demonstrates a remarkable specific capacitance of 1481.9 F g−1 at 1 A g−1 and an impressive cycling stability, holding 91.4 % of its initial capacitance even after 8000 cycles. The CSC@NiMn LDH//AC asymmetric supercapacitor device exhibits an impressive energy density of 103.5 Wh kg−1 at 800 W kg−1, coupled with superior cycling performance, retaining approximately 97.6 % after 10,000 cycles. This work offers a rational strategy to construct high-performance and eco-friendly supercapacitor electrodes. [Display omitted] •Biomass celery stem-derived porous carbon (CSC) provided an excellent 3D conductive matrix.•Hydrangea-like NiMn LDH nanospheres were uniformly grown on the CSC, resulting in a novel CSC@NiMn LDH composite.•The optimal CSC@NiMn LDH composite exhibited excellent capacitance performance.•The assembled ASC showed superior cycling stability with 97.6 % capacity retention after 10,000 cycles.